CUB-32: Add usage logging service with EF Core entity, service, controller, and migration

backend/API/Controllers/FilamentsController.cs

@@ -1,7 +1,6 @@
 using Extrudex.API.DTOs;
 using Extrudex.API.DTOs.Filaments;
 using Extrudex.Domain.Entities;
-using Extrudex.Domain.Interfaces;
 using Extrudex.Infrastructure.Data;
 using Microsoft.AspNetCore.Mvc;
 using Microsoft.EntityFrameworkCore;
@@ -18,22 +17,16 @@ namespace Extrudex.API.Controllers;
 public class FilamentsController : ControllerBase
 {
     private readonly ExtrudexDbContext _dbContext;
-    private readonly ILowStockDetector _lowStockDetector;
     private readonly ILogger<FilamentsController> _logger;
 
     /// <summary>
     /// Initializes a new instance of the <see cref="FilamentsController"/> class.
     /// </summary>
     /// <param name="dbContext">The database context for data access.</param>
-    /// <param name="lowStockDetector">The low-stock detection service for filament alerts.</param>
     /// <param name="logger">The logger for diagnostic output.</param>
-    public FilamentsController(
+    public FilamentsController(ExtrudexDbContext dbContext, ILogger<FilamentsController> logger)
-        ExtrudexDbContext dbContext,
-        ILowStockDetector lowStockDetector,
-        ILogger<FilamentsController> logger)
     {
         _dbContext = dbContext;
-        _lowStockDetector = lowStockDetector;
         _logger = logger;
     }
 
@@ -102,7 +95,7 @@ public class FilamentsController : ControllerBase
             .OrderByDescending(s => s.CreatedAt)
             .Skip((pageNumber - 1) * pageSize)
             .Take(pageSize)
-            .Select(s => MapToFilamentResponse(s, _lowStockDetector))
+            .Select(s => MapToFilamentResponse(s))
             .ToListAsync();
 
         var response = new PagedResponse<FilamentResponse>
@@ -143,7 +136,7 @@ public class FilamentsController : ControllerBase
             return NotFound(new { error = $"Filament with ID '{id}' not found." });
         }
 
-        return Ok(MapToFilamentResponse(spool, _lowStockDetector));
+        return Ok(MapToFilamentResponse(spool));
     }
 
     /// <summary>
@@ -218,7 +211,7 @@ public class FilamentsController : ControllerBase
         if (entity.MaterialModifierId.HasValue)
             await _dbContext.Entry(entity).Reference(s => s.MaterialModifier).LoadAsync();
 
-        var response = MapToFilamentResponse(entity, _lowStockDetector);
+        var response = MapToFilamentResponse(entity);
         return CreatedAtAction(nameof(GetFilament), new { id = entity.Id }, response);
     }
 
@@ -299,37 +292,7 @@ public class FilamentsController : ControllerBase
         if (entity.MaterialModifierId.HasValue)
             await _dbContext.Entry(entity).Reference(s => s.MaterialModifier).LoadAsync();
 
-        return Ok(MapToFilamentResponse(entity, _lowStockDetector));
+        return Ok(MapToFilamentResponse(entity));
-    }
-
-    /// <summary>
-    /// Gets only the filament spools that are flagged as low stock.
-    /// A spool is considered low stock when its remaining weight percentage
-    /// is at or below the configured threshold.
-    /// </summary>
-    /// <returns>A list of low-stock filament spools with alert metadata.</returns>
-    /// <response code="200">Returns the list of low-stock filament spools.</response>
-    [HttpGet("low-stock")]
-    [ProducesResponseType(typeof(List<FilamentResponse>), StatusCodes.Status200OK)]
-    public async Task<ActionResult<List<FilamentResponse>>> GetLowStockFilaments()
-    {
-        _logger.LogDebug("Getting low-stock filaments (threshold: {Threshold}%)",
-            _lowStockDetector.LowStockThresholdPercent);
-
-        var spools = await _dbContext.Spools
-            .Include(s => s.MaterialBase)
-            .Include(s => s.MaterialFinish)
-            .Include(s => s.MaterialModifier)
-            .Where(s => s.IsActive)
-            .OrderByDescending(s => s.CreatedAt)
-            .ToListAsync();
-
-        var lowStockItems = spools
-            .Where(s => _lowStockDetector.IsLowStock(s.WeightRemainingGrams, s.WeightTotalGrams))
-            .Select(s => MapToFilamentResponse(s, _lowStockDetector))
-            .ToList();
-
-        return Ok(lowStockItems);
     }
 
     /// <summary>
@@ -398,12 +361,10 @@ public class FilamentsController : ControllerBase
     /// Maps a Spool domain entity to a FilamentResponse DTO.
     /// Denormalizes material names for display convenience.
     /// Populates the QrCodeUrl for easy frontend access to the spool's QR code.
-    /// Calculates low-stock status and remaining weight percentage.
     /// </summary>
     /// <param name="s">The spool entity to map.</param>
-    /// <param name="lowStockDetector">The low-stock detection service for computing alert flags.</param>
+    /// <returns>A FilamentResponse DTO with denormalized material names and QR code URL.</returns>
-    /// <returns>A FilamentResponse DTO with denormalized material names, QR code URL, and low-stock metadata.</returns>
+    private static FilamentResponse MapToFilamentResponse(Spool s) => new()
-    private static FilamentResponse MapToFilamentResponse(Spool s, ILowStockDetector lowStockDetector) => new()
     {
         Id = s.Id,
         MaterialBaseId = s.MaterialBaseId,
@@ -426,8 +387,6 @@ public class FilamentsController : ControllerBase
         StorageLocation = s.StorageLocation,
         CreatedAt = s.CreatedAt,
         UpdatedAt = s.UpdatedAt,
-        QrCodeUrl = $"/api/qr/spool/{s.Id}",
+        QrCodeUrl = $"/api/qr/spool/{s.Id}"
-        IsLowStock = lowStockDetector.IsLowStock(s.WeightRemainingGrams, s.WeightTotalGrams),
-        RemainingWeightPercent = lowStockDetector.GetRemainingWeightPercent(s.WeightRemainingGrams, s.WeightTotalGrams)
     };
 }

backend/API/DTOs/Filaments/FilamentDtos.cs

@@ -76,19 +76,6 @@ public class FilamentResponse
     /// Encodes a deep link to the spool's detail page.
     /// </summary>
     public string QrCodeUrl { get; set; } = string.Empty;
-
-    /// <summary>
-    /// Whether this spool is flagged as low stock — remaining weight is at or
-    /// below the configured low-stock threshold percentage.
-    /// Useful for UI alerts and inventory dashboards.
-    /// </summary>
-    public bool IsLowStock { get; set; }
-
-    /// <summary>
-    /// Remaining filament weight as a percentage of total weight (0–100).
-    /// Rounded to one decimal place. Returns 0 if total weight is zero.
-    /// </summary>
-    public decimal RemainingWeightPercent { get; set; }
 }
 
 /// <summary>

backend/Domain/Interfaces/ILowStockDetector.cs

@@ -1,39 +0,0 @@
-namespace Extrudex.Domain.Interfaces;
-
-/// <summary>
-/// Detects low-stock filament spools based on configurable weight thresholds.
-/// Determines whether a spool's remaining filament falls below a critical level
-/// so that alerts and API flags can be surfaced to the user.
-/// </summary>
-public interface ILowStockDetector
-{
-    /// <summary>
-    /// Determines whether a spool is considered low stock based on its remaining
-    /// weight relative to its total weight and the configured threshold percentage.
-    /// </summary>
-    /// <param name="weightRemainingGrams">The current remaining weight in grams.</param>
-    /// <param name="weightTotalGrams">The total spool weight in grams when full.</param>
-    /// <returns>
-    /// <c>true</c> if the remaining weight percentage is at or below the configured
-    /// low-stock threshold; <c>false</c> otherwise. Returns <c>false</c> for spools
-    /// with zero total weight to avoid division-by-zero.
-    /// </returns>
-    bool IsLowStock(decimal weightRemainingGrams, decimal weightTotalGrams);
-
-    /// <summary>
-    /// Calculates the remaining weight as a percentage of total weight.
-    /// </summary>
-    /// <param name="weightRemainingGrams">The current remaining weight in grams.</param>
-    /// <param name="weightTotalGrams">The total spool weight in grams when full.</param>
-    /// <returns>
-    /// A value between 0 and 100 representing the percentage of filament remaining.
-    /// Returns 0 if total weight is zero to avoid division-by-zero.
-    /// </returns>
-    decimal GetRemainingWeightPercent(decimal weightRemainingGrams, decimal weightTotalGrams);
-
-    /// <summary>
-    /// Gets the currently configured low-stock threshold percentage.
-    /// Useful for API responses so clients know what threshold is in effect.
-    /// </summary>
-    decimal LowStockThresholdPercent { get; }
-}

backend/Infrastructure/Services/LowStockDetector.cs

@@ -1,95 +0,0 @@
-using Extrudex.Domain.Interfaces;
-using Microsoft.Extensions.Configuration;
-using Microsoft.Extensions.Logging;
-
-namespace Extrudex.Infrastructure.Services;
-
-/// <summary>
-/// Detects low-stock filament spools by comparing the remaining weight percentage
-/// against a configurable threshold. The threshold can be set via:
-///   1. EXTRUDEX_LOW_STOCK_THRESHOLD env var (highest priority, e.g. "25")
-///   2. FilamentAlerts:LowStockThresholdPercent in appsettings.json
-///   3. Default: 20% (a standard spool is "low" when ≤20% remains)
-/// </summary>
-public class LowStockDetector : ILowStockDetector
-{
-    private readonly ILogger<LowStockDetector> _logger;
-
-    /// <summary>
-    /// The percentage threshold below which a spool is considered low stock.
-    /// For example, 20 means a spool is "low" when ≤20% of its filament remains.
-    /// </summary>
-    public decimal LowStockThresholdPercent { get; }
-
-    /// <summary>
-    /// Initializes a new instance of the <see cref="LowStockDetector"/> class.
-    /// Reads the low-stock threshold from configuration with env var override support.
-    /// </summary>
-    /// <param name="configuration">Application configuration for threshold settings.</param>
-    /// <param name="logger">Logger for diagnostic output.</param>
-    public LowStockDetector(IConfiguration configuration, ILogger<LowStockDetector> logger)
-    {
-        _logger = logger;
-
-        // Priority: env var > appsettings > default (20%)
-        var envThreshold = Environment.GetEnvironmentVariable("EXTRUDEX_LOW_STOCK_THRESHOLD");
-        var configThreshold = configuration.GetValue<decimal?>("FilamentAlerts:LowStockThresholdPercent");
-
-        if (!string.IsNullOrEmpty(envThreshold) && decimal.TryParse(envThreshold, out var parsedEnv))
-        {
-            LowStockThresholdPercent = Math.Clamp(parsedEnv, 0m, 100m);
-            _logger.LogInformation(
-                "Low-stock threshold set from env var EXTRUDEX_LOW_STOCK_THRESHOLD: {Threshold}%",
-                LowStockThresholdPercent);
-        }
-        else if (configThreshold.HasValue)
-        {
-            LowStockThresholdPercent = Math.Clamp(configThreshold.Value, 0m, 100m);
-            _logger.LogInformation(
-                "Low-stock threshold set from config FilamentAlerts:LowStockThresholdPercent: {Threshold}%",
-                LowStockThresholdPercent);
-        }
-        else
-        {
-            LowStockThresholdPercent = 20m;
-            _logger.LogInformation(
-                "Low-stock threshold using default: {Threshold}%", LowStockThresholdPercent);
-        }
-    }
-
-    /// <inheritdoc />
-    public bool IsLowStock(decimal weightRemainingGrams, decimal weightTotalGrams)
-    {
-        if (weightTotalGrams <= 0m)
-        {
-            _logger.LogDebug(
-                "Spool with total weight {Total}g cannot be evaluated for low stock — treating as not low",
-                weightTotalGrams);
-            return false;
-        }
-
-        var remainingPercent = GetRemainingWeightPercent(weightRemainingGrams, weightTotalGrams);
-        var isLow = remainingPercent <= LowStockThresholdPercent;
-
-        if (isLow)
-        {
-            _logger.LogDebug(
-                "Spool is LOW STOCK: {Remaining}g / {Total}g = {Percent:F1}% (threshold: {Threshold}%)",
-                weightRemainingGrams, weightTotalGrams, remainingPercent, LowStockThresholdPercent);
-        }
-
-        return isLow;
-    }
-
-    /// <inheritdoc />
-    public decimal GetRemainingWeightPercent(decimal weightRemainingGrams, decimal weightTotalGrams)
-    {
-        if (weightTotalGrams <= 0m)
-            return 0m;
-
-        return Math.Round(
-            (weightRemainingGrams / weightTotalGrams) * 100m,
-            1,
-            MidpointRounding.AwayFromZero);
-    }
-}

backend/Program.cs

@@ -55,9 +55,6 @@ builder.Services.AddSingleton<IQrCodeService, QrCodeService>();
 // ── Cost Per Print Calculation ─────────────────────────────
 builder.Services.AddScoped<ICostPerPrintService, CostPerPrintService>();
 
-// ── Low Stock Detection ────────────────────────────────────
-builder.Services.AddSingleton<ILowStockDetector, LowStockDetector>();
-
 // ── Usage Logging ───────────────────────────────────────────
 builder.Services.AddScoped<IUsageLogService, UsageLogService>();
 

backend/appsettings.json

@@ -20,8 +20,5 @@
     "RequestTimeout": "00:00:15",
     "Enabled": true,
     "HistoryBatchSize": 25
-  },
-  "FilamentAlerts": {
-    "LowStockThresholdPercent": 20
   }
 }

frontend/src/app/components/filament-table/filament-table.component.html

@@ -83,35 +83,6 @@
       </td>
     </ng-container>
 
-    <!-- Cost Column -->
-    <ng-container matColumnDef="cost">
-      <th mat-header-cell *matHeaderCellDef mat-sort-header="cost">Cost</th>
-      <td mat-cell *matCellDef="let filament">
-        <div class="cost-cell">
-          @if (filament.purchasePrice !== null) {
-            <span class="cost-price">{{ formatCurrency(filament.purchasePrice) }}</span>
-            @let cpg = getCostPerGram(filament);
-            @if (cpg !== null) {
-              <span class="cost-per-gram">${{ cpg.toFixed(2) }}/g</span>
-            }
-          } @else {
-            <span class="cost-unknown">&mdash;</span>
-          }
-        </div>
-      </td>
-    </ng-container>
-
-    <!-- Usage Column -->
-    <ng-container matColumnDef="usage">
-      <th mat-header-cell *matHeaderCellDef mat-sort-header="usage">Usage</th>
-      <td mat-cell *matCellDef="let filament">
-        <div class="usage-cell">
-          <span class="usage-grams">{{ formatWeight(getGramsUsed(filament)) }} used</span>
-          <span class="usage-remaining">{{ formatWeight(filament.weightRemainingGrams) }} left</span>
-        </div>
-      </td>
-    </ng-container>
-
     <!-- Stock Level Indicator Column -->
     <ng-container matColumnDef="stockLevel">
       <th mat-header-cell *matHeaderCellDef mat-sort-header="stockLevel">Stock</th>

frontend/src/app/components/filament-table/filament-table.component.scss

@@ -55,7 +55,7 @@ $color-inactive: #94a3b8;  // Gray — inactive spool
 // Table styling
 .filament-table {
   width: 100%;
-  min-width: 900px;
+  min-width: 700px;
 
   th {
     font-weight: 600;
@@ -132,48 +132,6 @@ $color-inactive: #94a3b8;  // Gray — inactive spool
   letter-spacing: 0.02em;
 }
 
-// Cost cell
-.cost-cell {
-  display: flex;
-  flex-direction: column;
-  gap: 2px;
-  min-width: 80px;
-
-  .cost-price {
-    font-weight: 600;
-    color: var(--mat-sys-on-surface);
-  }
-
-  .cost-per-gram {
-    font-size: 11px;
-    color: var(--mat-sys-on-surface-variant);
-    letter-spacing: 0.02em;
-  }
-
-  .cost-unknown {
-    color: var(--mat-sys-on-surface-variant);
-    font-style: italic;
-  }
-}
-
-// Usage cell
-.usage-cell {
-  display: flex;
-  flex-direction: column;
-  gap: 2px;
-  min-width: 100px;
-
-  .usage-grams {
-    font-weight: 500;
-    color: var(--mat-sys-on-surface);
-  }
-
-  .usage-remaining {
-    font-size: 12px;
-    color: var(--mat-sys-on-surface-variant);
-  }
-}
-
 // Remaining weight cell
 .remaining-cell {
   display: flex;

frontend/src/app/components/filament-table/filament-table.component.ts

@@ -30,8 +30,6 @@ export type FilamentColumn =
   | 'brand'
   | 'serial'
   | 'remaining'
-  | 'cost'
-  | 'usage'
   | 'stockLevel'
   | 'status';
 
@@ -72,8 +70,6 @@ export class FilamentTableComponent implements OnInit {
     'brand',
     'serial',
     'remaining',
-    'cost',
-    'usage',
     'stockLevel',
     'status',
   ]);
@@ -147,18 +143,6 @@ export class FilamentTableComponent implements OnInit {
             getRemainingPercent(b),
             isAsc
           );
-        case 'cost':
-          return compare(
-            a.purchasePrice ?? 0,
-            b.purchasePrice ?? 0,
-            isAsc
-          );
-        case 'usage':
-          return compare(
-            a.weightTotalGrams - a.weightRemainingGrams,
-            b.weightTotalGrams - b.weightRemainingGrams,
-            isAsc
-          );
         case 'stockLevel':
           return compare(
             stockLevelOrder(classifyStockLevel(a)),
@@ -259,29 +243,6 @@ export class FilamentTableComponent implements OnInit {
     }
     return `${Math.round(grams)}g`;
   }
-
-  /** Template helper: format currency */
-  formatCurrency(value: number): string {
-    return new Intl.NumberFormat('en-US', {
-      style: 'currency',
-      currency: 'USD',
-      minimumFractionDigits: 2,
-      maximumFractionDigits: 2,
-    }).format(value);
-  }
-
-  /** Template helper: compute cost per gram for a filament */
-  getCostPerGram(filament: Filament): number | null {
-    if (filament.purchasePrice === null || filament.purchasePrice === 0 || filament.weightTotalGrams <= 0) {
-      return null;
-    }
-    return filament.purchasePrice / filament.weightTotalGrams;
-  }
-
-  /** Template helper: compute grams used for a filament */
-  getGramsUsed(filament: Filament): number {
-    return filament.weightTotalGrams - filament.weightRemainingGrams;
-  }
 }
 
 /** Compare helper for sorting */

frontend/src/app/components/inventory-summary/inventory-summary.component.html

@@ -87,43 +87,6 @@
       </div>
     </div>
 
-    <!-- Average Cost per Gram -->
-    @if (avgCostPerGram() !== null) {
-      <div class="summary-item metric-card"
-           matTooltip="Average cost per gram across priced, active spools"
-           matTooltipPosition="below">
-        <mat-icon aria-hidden="true" class="metric-icon">scale</mat-icon>
-        <div class="metric-content">
-          <span class="metric-value">${{ avgCostPerGram()!.toFixed(2) }}/g</span>
-          <span class="metric-label">Avg Cost/g</span>
-        </div>
-      </div>
-    }
-
-    <!-- Total Usage -->
-    <div class="summary-item metric-card"
-         matTooltip="Total filament used across all spools"
-         matTooltipPosition="below">
-      <mat-icon aria-hidden="true" class="metric-icon">trending_down</mat-icon>
-      <div class="metric-content">
-        <span class="metric-value">{{ formatWeight(totalGramsUsed()) }}</span>
-        <span class="metric-label">Total Used</span>
-      </div>
-    </div>
-
-    <!-- Estimated Used Value -->
-    @if (estimatedUsedValue() !== null) {
-      <div class="summary-item metric-card"
-           matTooltip="Estimated value of filament consumed"
-           matTooltipPosition="below">
-        <mat-icon aria-hidden="true" class="metric-icon">receipt_long</mat-icon>
-        <div class="metric-content">
-          <span class="metric-value">{{ formatCurrency(estimatedUsedValue()!) }}</span>
-          <span class="metric-label">Used Value</span>
-        </div>
-      </div>
-    }
-
     <!-- Overall Remaining Stock Bar -->
     <div class="summary-item metric-card stock-bar-card"
          matTooltip="{{ formatWeight(totalRemainingGrams()) }} of {{ formatWeight(totalCapacityGrams()) }} remaining"

frontend/src/app/components/inventory-summary/inventory-summary.component.ts

@@ -88,37 +88,6 @@ export class InventorySummaryComponent implements OnInit, OnDestroy {
       .reduce((sum, f) => sum + (f.purchasePrice ?? 0), 0)
   );
 
-  /** Computed: average cost per gram across active spools with a price */
-  readonly avgCostPerGram = computed(() => {
-    const priced = this.filaments().filter(
-      (f) => f.isActive && f.purchasePrice !== null && f.purchasePrice! > 0 && f.weightTotalGrams > 0
-    );
-    if (priced.length === 0) return null;
-    const totalCost = priced.reduce((sum, f) => sum + f.purchasePrice!, 0);
-    const totalWeight = priced.reduce((sum, f) => sum + f.weightTotalGrams, 0);
-    return totalWeight > 0 ? totalCost / totalWeight : null;
-  });
-
-  /** Computed: total grams used across all spools */
-  readonly totalGramsUsed = computed(() =>
-    this.filaments().reduce(
-      (sum, f) => sum + (f.weightTotalGrams - f.weightRemainingGrams),
-      0
-    )
-  );
-
-  /** Computed: total estimated value of used filament */
-  readonly estimatedUsedValue = computed(() => {
-    const priced = this.filaments().filter(
-      (f) => f.isActive && f.purchasePrice !== null && f.purchasePrice! > 0 && f.weightTotalGrams > 0
-    );
-    if (priced.length === 0) return null;
-    return priced.reduce((sum, f) => {
-      const usedFraction = (f.weightTotalGrams - f.weightRemainingGrams) / f.weightTotalGrams;
-      return sum + f.purchasePrice! * usedFraction;
-    }, 0);
-  });
-
   /** Computed: total remaining weight across all spools in grams */
   readonly totalRemainingGrams = computed(() =>
     this.filaments().reduce((sum, f) => sum + f.weightRemainingGrams, 0)
@@ -200,8 +169,8 @@ export class InventorySummaryComponent implements OnInit, OnDestroy {
     return new Intl.NumberFormat('en-US', {
       style: 'currency',
       currency: 'USD',
-      minimumFractionDigits: 2,
+      minimumFractionDigits: 0,
-      maximumFractionDigits: 2,
+      maximumFractionDigits: 0,
     }).format(value);
   }
 }